An elite soldier accusing Ben Roberts-Smith of mercilessly bullying a comrade and embellishing his wartime achievements says Australia needed to know of his alleged murderous war crimes.
The serving special forces soldier codenamed Person Seven admitted in the Federal Court he was one of two anonymous sources who appeared on 60 Minutes in 2019 in breach of Australian Defence policy.
"I am a senior NCO warrant officer in the army, I was told of an allegation of an egregious nature, I am not walking past that," he said on Thursday.
While he was not proud of speaking to the media and it was a mistake, he "wanted to be a voice from within".
"I wanted the Australian public to know".
He denied disparaging the war veteran's reputation due to an obsession with his awarding of the Victoria Cross, but admitted some of his discussion with an investigative journalist involved "petty immature childish gossip".
Mr Roberts-Smith has vehemently denied all allegations of wrongdoing and has argued the claims stem from jealous associates spiteful that he is one of a handful of Australian recipients of the VC since 1970.
The 43-year-old is suing The Age, The Sydney Morning Herald and The Canberra Times for defamation over reports claiming he committed war crimes and murders in Afghanistan between 2006 and 2012.
Person Seven said the former SAS corporal was "not a bright bloke" having seen him fail a routine medical exam twice in one day, but denied he was trying to "stick the knife in".
"(Mr Roberts-Smith) is like a frilled-neck lizard, when he is threatened it all comes forward, and when you put it on him he backs right off."
A cornerstone allegation the newspapers are seeking to prove in their defence of truth, centres on a 2012 Darwan mission where Mr Roberts-Smith is accused of kicking an unarmed and handcuffed Afghan prisoner off a cliff.
Person Seven said another soldier dubbed Person Four recounted the incident three times, saying he watched the man's head hit a rock and a "tooth flew out" causing a "wave of panic to come across his body".
"He realised then that he had to get out of that patrol," Person Seven said of Person Four.
Person Seven disclosed to journalist Christ Masters that Mr Roberts-Smith was never interested in charities until he received his VC and wanted insurance to make his reputation appear "squeaky clean".
Person Seven explained he thought it "rich" Mr Roberts-Smith was a patron for mental health when he had allegedly bullied another soldier to the point of major depression.
"Even if he smelled (Mr Roberts-Smith's) deodorant he had issues," he said.
At first the witness turned down appearing on 60 Minutes, until he found out Mr Roberts-Smith was waging a concerted threatening campaign to silence soldiers giving evidence to a secret inquiry, he said.
Person Seven also accused him of embellishing facts on his VC citation and said he stole credit away from another troop member who fought the 2010 Battle of Tizak.
He said two soldiers had been "coached and bullied" in writing their statements for Mr Roberts-Smith's VC by a close troop commander of his.
Person Seven said Mr Roberts-Smith admitted taking cocaine and steroids, and denied his evidence was motivated by jealousy.
It follows his evidence on Wednesday that he watched Mr Robert-Smith punch and knee and frightened Afghan prisoner and threaten to strangle a man.
The trial continues.
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